Xerographic induction recording



May 23, 1967 L. E. WALKUP 3,321,308

XEROGRAPHIC INDUCTION RECORDING lY HEATER 1,23

FG 3 TQ /f /2 ff@ l trzErS-Si135:52-23zggfgf;,-35 /36 I ///////////////////////////////////////lf HEATER 2a INVENTOR LEWIS E. wALKuP A T TORNEI vMay 23, 1967 E. WALKUP XEROGRAPHIC INDUCTION RECORDING 5 Sheets-Sheet Filed May 17, 1963 HEATER INVENTOR. LEWIS E. WALKUP @7% 30021 A T TORNE Y May 23, 1967 Filed May 17, 1965 L. E. WALKUP 3,321,308

XEROGRAPHIC INDUCTION RECORDING 5 Sheets-Sheet 1,1,

INTELLIGENCE SIGNAL IN HORIZONTAL SWEEP GENERATOR HIGH VOLTAGE SUPPLY 4a 47 r4l /fg YlllllllllllI/77] l -L\\\ Yi F/G. 7 2

INTELLIGENCE SIGNAL IN HORIZONTAL SWEEP GENERATOR HIGH VOLTAGE SUPPLY LEWIS E.` WALKUP ATTORNEY XEROGRAPHIC INDUCTION RECORDING Filed May 1'7, 1963 5 Sheets-Sheet fl INVENTOR. LEWIS E. WALKUP WM @QQ A T TORNE Y l 7 May 23, 1967 E. WALKUP 3,3215308 XEROGRAPHI C INDUCTION RECORDING Filed May 17, 1965 5 Sheets-Sheet 5 INVENTOR; LEwls E. wALKuP w53 @QL A T TOR/VE? United States `Patent O 3,321,308 XEROGRAPHIC INDUCTION RECORDING Lewis E. Walkup, Columbus, Ohio, assignor, by mesne assignments, to Xerox Corporation, Rochester, N.Y., a corporation of New York Filed May 17, 1963, Ser. No. 281,181 1 Claim. (Cl. 96--1.1)

This invention relates in general to xerography and in particular to deformation development of latent electrostatic images. This application is a continuation-iin part of application Ser. No. 200,848, filed Iune 7, 1962, now U.S. Patent No. 3,196,013.

In conventional xerography, the latent electrostatic image on a xerographic plate is developed by applying a particulate pigmented developer material characterized in that it is attracted selectively by a latent electrostatic image. Once the latent electrostatic image has been developed on a xerographic plate, there is no way to reuse the xerographic plate until the developedv image has been transferred and the plate cleaned of remaining developer material or the material has otherwise been cleaned olf the plate. Thus, conventionally, it has been the practice to `transfer the developed image from a xerographic plate to a copying paper and then by some means cleaning the remaining material oif the plate. Such transfer and/or cleaning procedures necessarily introduce a considerable time factor intosthe operation. In some instances, it has been found desirable to eliminate this time factor. Such instances occur, for example, inthe. cases of television, facsimile and radar applications where it is desired to display the image and then immediately replace it with further images in fairly rapid succession.y It has been suggested that a liquid or thermoplastic layer over the surface of the xerographic plate may be deformed by the effects of the latent electrostatic image and may then be displayed by the use of Schlieren optics or the like. In the case of the liquid layer, the image is erased by removal ofthe electrostatic image. In thecase of the thermoplastic layer, the image is formed by softening the layer in the presence of the latent electrostatic image and islater erased by removing the electrostatic latent image and softening the thermoplastic material. It is plain, however, this this suggestion also involves a considerable de lay factor. Although it is not necessary to remove one developer material and add further developer material, the plate cannot be used for. a second image until the first image has been displayed and erased.

Now in accordance wtihthe present invention, ithas been found that such a.deformation image on a liquid'o'r lthermoplastic layer may be formed on such a layer that is spaced or separable froma latent image-'bearing member sothat the layer may be removed from proximity with the latent image-bearingmember, displayed, erased and then returned for reuse while the Xerographic plate may be used in the meantime. Also, it has been found that vlatent electrostatic images maybe formed by pin tubes, i

charactron tubes, Lenard window tubes, and the like on a variety of insulating surfaces, and then used to produce a deformation image on a spaced separable or inseparable layer. To. achieve this, the present invention encompasses methods and means of deforming auseparate orseparable layer by the induction effects. ofvan electrostatic latent image. Thus, it is an object of the invention to `deiine methods of deforming a deformable layerby. electrostatic induction.l

VIt is a, further object to define a methodof deforming a liquid layer by induction effects of a .latent electro; static image. l

It is a further object to define a methoduof deforming a deformable plastic by induction from a latent electrostatic image.

It is a further object to define a method and structures for deforming a deformable layer by induction from an image produced by a cathode-ray tube.

And, it is a further object to define novel methods and means for simultaneously forming an electrostatic image and an induced deformation image.

Further objects and features of the invention will become apparent while reading the following description in connection with the drawings wherein:

FIGURE l is a diagrammatic illustration of induction deformation of a liquid layer.

FIGURE 2 is a diagrammatic illustration of induction deformation of a thermoplastic layer.

FIGURE 3 is a diagrammatic illustration of induction deformation of the interface between a conductive liquid layer and an insulating thermoplastic layer.

FIGURE 4 is a diagrammatic illustration of induction deformation of the interface between an insulating liquid layer and a conductive thermoplastic layer.

FIGURE 5 is a diagrammatic illustration of induction deformation of the interface between an insulating liquid layer and a conductive liquid layer.

FIGURE 6 is a diagrammatic illustration of induction deformation of the interface between a conductive thermoplastic layer and an insulating thermoplastic layer.

FIGURE 7 is a diagrammatic illustration of an embodiment for forming a latent electrostatic image With a pin tube.

FIGURE 8 is a diagrammatic illustration of an embodiment of the invention for induction deformation with a Lenard window tube.

FIGURE 9 is a diagrammatic illustration of an embodiment of the invention for induction deformation with a charactron tube.

FIGURE 10 is a digrammatic illustration of apparatus inaccordance with the invention for induction deformation readout from a cathode-ray tube.

The present invention utilizes the physical effects of electrical field forces for image reproduction. Thus, the elds emanating from an electrostatic latent image may be used to displace material in such a way as to form a useable image. In one embodiment of the invention, as shown in FIGURE 1, plate 10 carries latent electrostatic image 13. This image may be previously formed in a conventional xerographic manner as by electrostatically charging insulating layer 1.2 and, if layer 12 is Photoconductive, exposing it to an image pattern to selectively dissipate some of the charge. The xerographic plate as shown comprises layer 12 of a photoconductive insulating ma terial such as vitreous selenium, zinc oxide in a binder, or other known photoconductive insulator, and conductive backing 11 such as brass, aluminum, conductive paper, glass with a conductive coating of tin oxide or the like.

y As illustrated, layer 12 hasbeen charged positively, and

the charges have been dissipated in the areas where the layer has been illuminated. The charges remaining after forming the electrostatic latent image emanate elds or `lines of force in the direction of available charges of the opposite polarity. Thus, these positive charges as illustrated will emit lines of force in the direction where there are no charges indicated on the surface of the layerr or elsedown through the layer to the conductive layer underneath.

In accordance with the invention, xerographic plate 10 bearing the latent electrostatic image is maintained in the dark and is positioned on supports 14 immediately over the image plate 15 comprising a conductive layer 16 which may suitably be made of conductive paper, metal, or other conductive material, and a conductive liquid layer 17 such as water, alcohol, mercury, Aquadag (Acheson Colloids Corp), or a liquiiied conductive resin material. The two plates are positioned as closely together as possible while avoiding actual physical contact. Thus, gaseous space 19 is maintained rbetween the adjacent surface preferably with a gap Width of between 1 and 5 mils. A narrower gap width presents too great a problem in precisely positioning the plates and raises the probability of dielectric breakdown which produces image defects. A gap width exceeding about 5 mils reduces the field eects obtained, lowers the quality of the reproduced image and reduces resolution and contrast. With the conductive liquid layer connected in common, through ground and conductive backing plates 11 and 16, to the back rof xerographic plate 10, the electrical charges representing the latent electrostatic image attract charges of opposite polarity to the adjacent areas of conductive liquid 17. As a result, the lines of force emanating from the latent electrostatic image find proximate points of opposite polarity charges in the liquid layer 17 and exert physical forces of attraction on those charges producing a deformation in the liquid layer. As illustrated in FIGURE l, the surface of liquid layer 17 is displaced in accordance with the latent electrostatic image to form relief image 18.

An embodiment of the invention similar to that illustrated in FIGURE l is shown in FIGURE 2` wherein deformable layer 21, which is a solid at normal room temperatures, is used in place of the liquid layer 17 in FIG- URE l. Thus, deformable layer 21 is appropriately a thermoplastic material such `as esters of hydrogenated rosin sold as Staybelite by Hercules Powder Co., styrene and styrene homologue resins sold as Piccolastic by Pennsylvania Industrial Chemical Corp., Amberol sold by Rohm and Haas Co., and other thermoplastic materials preferably having softening temperatures between about 90 F. and 200 F. in order to maintain stability at room temperature and yet soften readily for image formation.

Such plastic materials are -commonly electrically insulating, but their conductivity is readily increased by appropriate additives. Thus, when there is no desire to pass light through the deformable layer, the plastic may contain carbon black or like conductivity agent such as a dag graphite suspension obtainable from Acheson Colloid Corp.

Where it is desirable to expose through the deformable layer, it is necessary to use an additive that will not reduce the transparency of the layer. Stannic chloride has been found suitable for this purpose.

Throughout this specification, the relatively conductive deformable layer is described as conductive This is not intended to mean conductive in the general sense, but rather in the sense specific to the electrophotographic art. In the general sense, conductors are considered to have resistivities of less than 1 ohm-cm. Semiconductors are considered to occupy the range up to 109 ohm-cm., and materials with still higher resistivities are considered insulators. In electrophotography insulators are generally considered to be materials having resistivities of 1013 ohm-cm. and higher with materials capable of some charge retention having resistivities higher than l010 ohm-cm. Thus, for electrophotographic purposes, it is conventional to speak of materials with lower resistivities than 1010 ohm-cm. as conductors. While no line line can really |be drawn, it is necessary for the present invention that the material used have a number of free charges available with suflicient mobility to neutralize induced potential differences without any substantial time lag. Accordingly, it is the intent that throughout the present disclosure, conductive shall be interpreted to include resistivities of 1010 ohm-cm. or less.

The deformable layer 21 is supported by a conductive layer 22 against which is appropriately positioned a heating element 23. After the xerographic plate carrying the latent electrostatic image is positioned adjacent to the deformable layer, the deformable layer can be liquified by energizing heating element 23. The deformable layer will deform in the image pattern as described in connection with FIGURE 1 during the liquid phase, and then upon deenergization of the heating element, the deformable layer will freeze in the image pattern and may be removed from the presence of the latent electrostatic image for separate use. Re-heating in the absence of the latent electrostatic image will cause complete erasure of the image.

An embodiment of the invention for simultaneous formation of both the latent electrostatic image and the induction deformation image is illustrated in FIGURE 3. The embodiment of FIGURE 3 has the advantage of not requiring separate movement of the xerographic plate 10 and the image plate 15 during the process step. A further advantage is that no corona charging is used, reducing the required voltage, equipment, and process steps. Also, this can work in a vacuum where corona charging is not possible. Thus, a xerographic plate 10 such as described in -connection with FIGURE 1 is positioned in a sandwich with a deformable insulating layer 25 and a conductive liquid layer 26 in turn supported by a conductive backing 27. The deformable layer 25 which coats the conductive liquid layer 26 serves a dual function of providing a layer which may be frozen in a deformed condition and also providing an insulating barrier between the conductive liquid 26 and the photoconductive insulating layer 12. With this insulating barrier 25, it is possible to reduce the spacing between the photoconductive insulating layer andthe conductive liquid layer down to a gap in the order of 5 microns or more. With this decrease in spacing gap as compared to the embodiment of FIGURE 1, improved image contrast and resolution is obtainable. As well as various thermoplastics listed in connection with FIGURE 2, the deformable layer 25 in FIGURE 3 is appropriately low melting point paraffin. A voltage is applied between the conductive layers 11 and 27 from a voltage source 28. While conventionally the voltage used for charging a xerographic plate is in the order of several thousand volts, in the embodiment of FIGURE 3, the desired effects may be obtained by a considerably lower potential so voltage source 28 is accordingly in about the range of volts or higher. The limiting high voltage is one that would cause a dielectric breakdown in insulating layer 25 lor photoconductive insulating layer 12. The sandwich of layers is heated as by a heating element 23 so as to liquify the deformable layer 25 to a highly compliant condition. The photoconductive insulating layer is exposed to a light image as by a projector 31 as illustrated in FIGURE 3. The backing layer of the Xerographic plate is made of a transparent material such as glass coated with a conductive layer such as tin oxide. This permits exposure of the photoconductive insulating layer 12 through the back of the Xerographic plate. Under the influence of the light image, the electrical capacity of the sandwich varies in the image configuration. A greater charge density is achieved in the discrete areas of relatively greater capacity producing stronger field effects and selectively deforming both the conductive liquid layer 26 and the deformable layer 25 which yields to the forces induced in the conductive layer 26. When the heating element is disconnected, the deformable layer 25 will freeze, producing a fixed deformed interface between it and the liquid layer 26. The image plate with the deformed frozen layer and the liquid layer may then be removed from the xerographic plate and an image projected from it by virtue of differences in refraction at the deformed interface. One of the advantages that is obtained in this embodiment and similar embodiments discl-osed below is that when both the insulating deformable layer and the conductive deformable layer are in a liquid state the effects of surface tension and the like are greatly reduced and viscosity of the layers offers the principle resistance to deformation.

FIGURE 4 illustrates the variation of the embodiment of FIGURE 3 in which an insulating liquid layer 35 is` positioned between the latent electrostatic image-bearing surface and a conductive deformable layer 36. In this embodiment, layer 36 is made of a material that is solid at room temperature and readily liquies on the application of heat. This has a slight advantage over the embodimentof FIGURE 3 in that the thermally liquiable layer 36 is closer to the heat source 23. Thus, in FIGURE 4, the heating requirements are slightly less, and there is less chance of deterioration of the xerographic plate due to repeated application of heat.

The use of an insulating liquid and a conductive liquid is illustrated in FIGURE 5 in which an insulating liquid 38 is positioned in between the latent electrostatic imagebearing surface and a conductive liquid layer 39. These two liquid layers must be selected so as to be non-miscible, and the insulating liquid must have a lower density than the conductive liquid. For example, the conductive liquid may be water and the insulating liquid may be oil. In the embodiment of FIGURE 5, the resistance against the deformation etfects of the latent electrostatic image is produced almost entirely by liquid viscosity and interfacial tension between the two liquids. Since materials may be selected to minimize interfacial tension, deformation is readily obtained enabling the use' of lower voltages, thinner layers, and larger solid relief areas.

In FIGURE 6, both the insulating deformation layer and the conductive deformation layer are made of thermally liquia'ble materials that are solid at normal room temperatures. With both of these layers made of a material such as thermoplastic, it is possible to strip them apart after the image has been formed and solidified so as to obtain two separate deformation images. In this embodiment, the conductive layer would have a direct reading image, while the insulating layer would have a mirror reverse image on its deformed surface. In FIG- URE 6, as well as in FIGURE 3, vit is possible to use an insulating layer that is bonded permanently to the photoconductive insulating layer of the xerographic plate. However, this would require slightly different Xerographic steps from those customarily used. Thus, sensitzing the plate would have to be performed by a method such as disclosed in U.S. Patent 2,833,930 in which charge is induced to the photoconductor surface under illumination and then trapped at the surface by discontinuing the illumination.

FIGURES -3, 4, 5, and 6 are all illustrated with a voltage source 28 .applied across the conductive layers 11 and 27. However, if a latent electrostatic image is formed on xerographic plate 10 beforethe layers are sandwiched together, the common electrical reference connections as shown in FIGURES l and 2 produce the desired results. It is also possible to charge plate `10, then sandwich the 4layers together, .and .then form the latent image by exposing with a light image through a transparent side of the sandwich.4 In this latter case,- eithera common reference as in FIGURES l and .2 or a voltage source 28. connected between layers 11 and` 27 williestablish the desired references for deformation.

While the embodiments of the invention illustrated in FIGURES `1 'through 6 have all been described using the xerographic plate as the latent image-forming member, various other methods and apparatus for forming a'latent electrostatic image have been found operative. Particularly where it is Idesirable to print out images in a facsimile receiver or in electronic computers or informati-0n retrieval equipment, it is desirable to reproduce information supplied through a cathode-ray'tube or comparable device. Thus, FIGURES 7, 8, 9 and l0 are directed to the .embodiments of the invention which are particularly applicable' for use with such electronic equipment.

Referring to FIGURE 7, plate -40 is analogous to lxerographic plate 10 in FIGURES 1 through 6. However, electrically insulating layer 41 is a layer of most any electrically insulating material having a'resistivity higher than 1013 ohm-cm., and no photoconductive layer is used. Appropriate materials are plastic materials such as polyethylene terephthalate, polyvinyl chloride, or a highly insulating acrylic plastic, polyethylene, or acetate material. Glass is also suitable where llexibility is not desired. Generally, the material used for this insulating layer should maintain dimensional stability when exposed to temperatures of at least 200 F. and maintain electrical resistance of greater than l013 ohm-cm. under the same temperature range up to at least 200 F. tPlate 40 also has a conductive backing 42 of metal or, in some cases, a transparent material with a conductive transparent coating such as glass or a transparent plastic coated with tin oxide, copper iodide, or the like. As illustrated in FIGURE 7, a type of cathode-ray tube 43, known in the art as a pin tube, can be used to form a latent electrostatic image on plate 40. A more detailed description of pin tubes may be found in U.S. Patent 3,001,848 to L. E. Walkup. Pin tube 43 generally consists of cathode-ray gun structure 45, deflection plates 46 and face 47 of glass :or other highly insulating material in which a plurality of conductive pins 48 are embed-ded in a uniform array. Conductive layer 42 Iof plate 40 is connected to a reference potential in common with the electrical circuits operating pin tube 43. In operation, face 47 of the pin tube is positioned in proximate contact with the surface of layer 41. Electron gun 45 generates a cathode-ray beam which is caused to sweep back and forth in a uniform pattern across pins 48. The cathode-ray beam is intensity modulated by control signals in accordance with the intelligence to be reproduced. Whenever the intensity of the beam exceeds the level for electrical breakdown of the space between the pins and insulating layer 41 while rit is in contact with a particular pin or group -of pins, an electrical charge transfer is produced between the pin or pins and the surface of insulating layer 41. While pin tube 43 selectively transfers charge to member 40 in accordance with the intelligence to be reproduced, relative movement (indicated by ,arrow 50) between pin tube 43 and member `40 enables the continual presentation of new surface for the pin tube to act on. After a latent electrostatic image has been formed in accordance with FIGURE 7, plate 40 may be substituted for plate 10 in embodiments similar to those illustrated in FIGURES 1 through 6 in which the latent electrostatic image is formed separately from the deformable layers.

While FIGURE 7 is illustrated using a pin tube, other forms of cathode-ray tubes capable of producing latent electrostatic images may be used as will =be seen in the embodiments Ibelow.

With the layer for carrying the latent electrostatic charge pattern positioned adjacent or permanently bonded in a sandwich with the deformable layers during formation of the latentelectrostatic image, development -of the deformation image can be performed without the necessity of in-between handling. Accordingly, FIGURE 8 illustrates an embodiment of the invention comprising aV support layer 51 coated with a conductive layer 52. This arrangement of layers 51 and 52 is preferred when a transparent support is desired since the support layer 51 can be glass or transparent plastic coated with a transparent` conductive material such as tin oxide or copper iodide. Such transparency is usually desirable, since the preferred utilization of the deformation image is by transmission of light through the deformed layers. It should be understood, however, that, where light transmissibility isnot a desired characteristic for the sandwich, a single conductive layer such as a metal plate maybe usedinstead of the two layers 51 and 52. Over the conductive coating 52, a deformable conductive layer 53 either liquid or solid of a low viscosity when heated is applied. This material may have the characteristics of any of the conductive deformable materials previously disclosed and, for the reasons just given, is preferably transparent. `Insulating deformable layer 55 is -applied over conductive deformable layer S3. This insulating deformable layer should have a resistivity `of l013 ohm-cm. or higher as previously described and may suitably be a low softening point plastic material such as Staybelite Ester or Staybelite Ester available from the Hercules Powder Company, Piccolastic A-50 or Piccolastic A-75 available from Pennsylvania Industrial Chemical Company ior lother material that is soft or softenable at a temperature between about 90 F. and 200 F. to a viscosity between :about 104 and 107 poises. It is a further requirement, :as previously stated, that the deformable insulating layer 55 and the deform-able conductive layer 53 be non- 'miscible They may be separable or non-separable, but `where both layer 53 and layer 55 are deformable solid materials, it has been found preferable to bond them permanently together to minimize non-uniformity of contact. Where one of the layers is a liquid, uniformity can be achieve-d readily without permanent bonding. Where readout; 0f the image is to be by light transmitted through .the sandwich, it is a further desirable characteristic that 4a high refractive index differential exist between the two Ideformable layers. Where the deformable layers are permanently bonded together and the image is to be readout Iwhile the layers are so bonded, it becomes essential that .refractive index differential exist between the materials zso that the image can be detected. The difference in absolute refractive index is preferably about .2 or greater if no special optics are to be used for viewing. Where a schliefen or other contrast enhancing optical system is permissible, the difference in refractive index may be as low as .05 as long as the layers have a high optical quality and foreign material such as dust is very minimal. De- Vformable insulating layer 55 is, in turn, bonded to a highly insulating support layer 56. Support layer 56 in this embodiment serves a dual purpose. First, it acts as a lsurface for receiving and maintaining the latent electro- .static image, and, secondly, it operates as a non-deformable support to prevent deformation of deformable layer .55 except at the interface between layer 55 and layer 53. 'Support layer 51 and support layer 56 serve the further function of incapsulating and providing a protective cover Vfor the deformable material and for the deformation irnzages after they are formed. The cathode-ray tube 57 is positioned over the surface of insulating support layer 56 for forming the latent electrostatic image. This cath- `ode-ray tube is essentially similar to that illustrated in FIGURE 7 and operates in the same way except that instead of having a face carrying a multiplicity of conductive pins it has a face area that is substantially transparent to electron flow, thus permitting the electrical charges in the cathode-ray beam to flow directly through the face of thetube and impinge on the insulating surface of .support layer 56. This electron transparent face :area 58 is known to the art as a Lenard window. An example of a Lenard window tube is given in U.S. Patent 2,200,741. In the embodiment of FIGURE 8, the conductive layer 52 is connected to a common reference potential with the operational circuits of cathode-ray tube 57 so as to attract the electrical charges deposited by the electron beam. Heating element `60 of any conventional type for supplying heat is positioned adjacent to the sandwich structure to supply the necessary heat permitting deformation of deformable layers 53 and 55. This heating may be simultaneous with the formation of the latent electrostatic image from cathode-ray tube 57, or it may be in a later step.

FIGURE 9 illustrates an embodiment using a sandwich structure essentially identical to that of FIGURE 8, but using a different form of cathode-ray tube. In this embodiment, pin tube `62, essentially similar to that used in FIGURE 7, is modi-tied by use of a character forming screen 61 in the nature of that commonly found in charactron tubes. See U .S. Patent 2,777,745 for examples of charactron tubes. This screen 61 is a plate containing minute shaped holes in the configuration of alphabetical letters and the like. Control circuits for supplying the intelligence to be reproduced are so designed as to position the electron beam in coincidence with the desired characters to be reproduced in ya sequence determined by the signals carrying the intelligence. Thus, in this instance, the electron beam, shaped in the form of a given character, coincides with a series of pins v63 according to the pattern of the character and prints the latent electrostatic image on the insulating support layer character by character rather than by painting it von in a continuously sweeping motion as is the case for FIGURE 8.

While many obvious applicationsv are apparent for the present invention, one that is felt to be of particular interest at present is its ready utilization as a printout and storage medium .for electronic devices using cathode-ray tube displays. An exempl-ary embodiment of such a utilization is illustrated in FIGURE l0. The apparatus of FIGURE 10 uses separable deformable layers so that only the insulating support layer Vand the insulating deformable layer need be transparent. The apparatus comprises a conductive drum 70 rotated by a motor 71 with slip-clutch operated drive to supply reel 72 and take-up reel 73. Positioned around the drum in the direction of rotation is a bath station 75 for applying a -coating of conductive liquid 74 to the drum surface, a latent electrostatic image-forming station 76 depicted las a pin tube and a developing station 77 for heat development of the deformation image. Between supply reel 72 and drum 70 is an erasure station 78 comprising a high intensity heat source 80 and a black plate 81 for absorbing and concentrating infrared energy in the form of heat. Between take-up reel 73 and drum 70, an optical readout station is illustrated comprising a light source 82, a collimating lens 83, annular ring grating 84, a .focusing lens for focusing the image of grating 84 at second annular grating 86 and a projection lens 87 for focusing the deformation image on an image receiving member 88. This constitutes a Schlieren optical system for detecting and projecting the deformation image.

In operation, an imaging web of insulating transparent support layer 90 coated with deformable insulating layer 91 is placed in supply reel 72, passed in between high intensity heat source 80 and black plate 81 of erasing station 7 S around a portion of drum 70 with the deformable layer adjacent to the dr-um surface and on through the Schlieren projection system to take-up reel 73. With drum 70 revolving, the imaging web is drawn through erasure station 78 which heats the web causing erasure of any residual deformation image thereon. The web then comes in contact with the conductive liquid placed on the surface of drum 70 by bath station 75. As it passes under latent electrostatic image-forming station 76, a latent electrostatic image is recorded on the surface of layer 90. The motion of the web past the image-forming station may be compensated for by the proper control circuitry operating the cathode-ray tube as disclosed by way of eX- ample in U.S. Patent 2,736,770. This provides for a displacement of the cathode-ray sweep in the direction of and synchronized with the movement of the web. For this purpose, .a pin m-atrix for the pin tube would have to have adequate vertical width to cover this sweep displacement. In embodiments where the imaging member stops during cathode-ray operation, then moves a line at a time, only a single row of pins can be utilized as in FIGURE 1. After the latent electrostatic image has been formed on the surface of the insulating support layer, the web is oarried past development station 77 where heat softens deformable layer 91 so that the induction effects of the latent electrostatic image produces a deformation in accordance with the image at the interface of the conductive liquid coating and deformable layer 91. As the image-forming web passes on around drum 70, it cools again freezing the deformation image before separating from the surface of the drum. After leaving the surface of the drum, the deformable Web passes through the Schlieren projection system and onto take-up reel 73. The deformation image may be readout of the web by the Schlieren projection system 3S it passes on to take-up reel 73 or optionally it may be readout at a later time in a separate projection system. As a portion of the circumference of drum 70` separates from the image-forming Web, it is carried through bath station 75 Where the conductive liquid coating is cleaned and restored to uniformity. A portion of the conductive liquid tends to remain on the deformable surface of the image-forming web. In the embodiment of FIG-URE 10, this remaining portion of liquid serves a further useful purpose Iin acting as a cleanable coating over the deformable surface of the web so that foreign material such as dust and lint does not become permanently embedded in the web. Thus, when it is desired to erase and reuse a reel of the material, a Wiper blade 92, positioned just before contact of the web with drum 70 'as it is drawn from supply reel .'72, removes the residual conductive liquid along with stray foreign material that would otherwise be detrimental in the reuse of the web.

What is claimed is: A method of deformation recording by induction comprising:

(a) coating a deformable layer of conductive material over a dimensionally stable conductive support layer; (b) coating a softenable layer of insulating material having a thickness range of microns to 5 mils over a dimensionally stable insulating support layer; (c) positioning said softenable layer in uniform contact against said deformable layer; (d) connecting said conductive support layer to an electrical reference in common with a cathode ray 10 tube of a type designed to pass electrical charges from the cathode ray beam through the face of the tube;

(e) selectively charging said insulating support layer by said cathode ray tube to form a latent electrostatic image corresponding to modulations of said cathode ray beam; and,

(f) softening said softenable -layer to compliancy so that charges induced between the interface of said softenable layer and said deformable layer produce a relief image at said interface in the pattern of said latent electrostatic image.

References Cited by the Examiner UNITED STATES PATENTS 2,200,741 5/1940 Gray 346--21 X 2,616,961 11/1952 Groak 96-1 `2,777,745 l/ 1957 McNaney 96-1 X 2,879,422 3/1959 `Borden et al 96-1 X 3,008,066 11/ 1961 Mewberry 96-1 3,040,124 6/1962 Camras 346-74 3,055,006 9/1962l Dreyfoos 96-1 X 3,162,104 12/1964 Medley 96-1 3,196,013 7/1965 Walkup 96--1 NORMAN G. TORCHIN, Primary Examiner.

D. PRICE, I. RAUBICHE'K, C. E. VAN HORN,

Assistant Examiners. 

